Physicum seminar

Physicum seminar: Controlled and Explosive Nuclear Energy: Why Weapons Work Better Than the Power Plants?

On Thursday, 27. March 2025 at 4:15 p.m. in Physicum A106 and Zoom

Dr. Indrek Renge (UT)

Energy can be generated either by fusion of small nuclei or by fission of super heavy ones, and released either explosively or in a controlled fashion, corresponding to H- and A-bombs, and reactors, respectively. An example of hundreds of possible fission reactions can be as following:

²³⁵₉₂U + ¹₀n → ²³⁶₉₂U* → ⁹⁰₃₇Rb(β 2.9 min) + ¹⁴²₅₅Cs(β 2.3 s) + 4¹₀n + hν (X, γ) (202 MeV);
* mark short-lived excited U nucleus, and bold mass number the neutron (n) rich products. Because of n multiplication, fission is a chain process, while fusion is not. The explosion is promoted by fast, ~1 MeV-n, while the thermal, moderated 25 meV-n work in most reactors. Historically, the explosions materialized first (in 1945). Although touted as clean and “green”, the nuclear power is stagnating at present for many reasons: technical, economic, political, and environmental. If the fuel rods are not reprocessed (they rarely are), the U utilization efficiency of such “once-through” technology is only one to >130 U atoms, remaining in burnt-out fuel contaminated with n poisons, plus a huge mass of depleted U left over after isotopic enrichment. Potentially, about 200 MeV of energy is obtained from abundant fertile ²³²Th and ²³⁸U, with the help of extra n sources, such as spallation or fusion.
The deuterium and tritium (D+T) fusion proceeds in a small scale relatively easily in accelerators and different reactors; T can be replenished using n and Li in a fuel cycle:

³₁T + ²₁D → ⁴₂He + n + 17.6 MeV;
n + ⁶₃Li → ⁴₂He + ³₁T + 4.78 MeV.
The fusion reactors as a source of practically unlimited carbon-free energy have not yet reached technological maturity. By contrast, the design of thermonuclear weapons by Teller and Ulam from 1951, basing on these equations, remained unknown until 1980, when the investigations by several activists (Howard Morland, Chuck Hansen) showed them be compact, lightweight, and extremely powerful (a device with 1 MT TNT equivalent can have mass of only 300 kg).

The Physicum seminars are meant for a broad auditorium of physicists and materials scientists, as well as for interested people from other natural and exact sciences (including bachelor level students) and aim at introducing what is important and new in a certain field, or where a specific research direction has reached today.

Seminar is in Estonian. Everyone is welcome to participate.

2024

56. Dr. Velle Toll (UT) "The impact of human activity on clouds"

55. Dr. Taavi Repän and Dr Artjom Vargunin (UT) "Nobel Prize in Physics 2024"

54. Prof. Mikko Sipilä (University of Helsinki, Finland) "How do secondary aerosols form in polar atmospheres?"

53. Dr. Vinoth Balasubramani (KAUST, Saudi Arabia) "Holographic tomography: label-free 3D imaging and inference of live cells and organoids"

52. Book Presentation: Galileo Galilei "Arutlusi ja matemaatilisi tõestuskäike" and John D. Barrow "Uued kõiksuse teooriad"

51. Dr. Jitraporn (Pimm) Vongsvivut (ANSTO ‒ Australian Synchrotron) "Advances in High-Resolution Chemical Imaging Capabilities at Australian Synchrotron’s Infrared Microspectroscopy (IRM) Beamline and Their Key Research Applications"

50. Daniel Smith (Swinburne University Australia) "Laser Fabrication of Sapphire Optics for Astronomy Application"

49. Kristjan Eimre (EPFL) "High-throughput, reproducible and open computational materials research"

48. Indrek Renge (UT) "Small Modular Reactors (SMRs): Hope or Hype?"

47. Jaak Kikas (UT) "Abiological life"

46. Kaarel Piip "Kaitseväe Akadeemia elektroonilise võitluse kompetentsikeskuse tegemistest"

2023

45. Dr. Tomi Sebastian Koivisto (UT) "On the metageometric foundation of physics".

44. Prof. Peeter Saari (UT) "Laservälke kestuse lühenemisest poole sajandiga 15 suurusjärku ja Nobeli füüsikapreemiast 2023."

43. Prof. Ivo Ihrke (University of Siegen, Germany) "Computational Microscopy: Beyond the First Order"

42. Prof. Tommi K. Hakala (University of Eastern Finland) and Dr. Antti J. Moilanen (ETH Zürich) "Lasing and Bose-Einstein condensation in plasmonic lattices"

41. Prof Raul Vicente Zafra (University of Tartu) "Artificial Neural Networks - basics and relation to physics and statistical physics models"

40. Dr Matthias Weiszflog and Inga Goetz (Uppsala University) "3D printing of metallic glasses and composites, Neutron diagnostic for fusion plasmas and Collaborative physics teaching"

39. Dr Ujjal Gautam (Indian Institute of Science Education and Research Mohali) "Chemistry with waste plastic: pollution remediation, oxygen harvesting, and solar energy utilization"

38. Raivo Jaaniso (UT) "Graphene Flagship and E²-nose"

37. Mart Maasik (CEI, UT), Aivar Pere (CEI, UT), Triinu Lööve (CEI, UT), Siimeon Pilli (CEI, UT), Vallo Mulk (Grant Office, UT) "Introduction of the activities of the Centre for Entrepreneurship and Innovation of the University of Tartu"

36. Prof. Joseph Rosen (Ben-Gurion University of the Negev, Israel) "3D Imaging Using Coded Aperture Digital Holography"

2022

35. Dr Marta Berholts (UT) "Quantum watch based on a Rydberg wave packet"

34. Prof. Saulius Juodkazis (Swinburne University of Technology, Australia) "Ultra-short laser pulses as material synthesis, lithography, characterisation tool"

33. Dr. Sergei Vlassov (UT) and Elyad Damerchi (UT) "Real-time observation of heat-induced effects in micro- and nanostructures inside a scanning electron microscope"

32. Laur Järv (UT), Peeter Saari (UT) and Johannes Heinsoo (IQM Finland OY) "Nobel Prize in Physics 2022"

31. Artur Tamm (UT) "Short range order in a high entropy alloy and its role in vacancy energetics and hydrogen trapping"

30. Martin Sláma (TESCAN) "TESCAN FIB/SEM system and TEM lamella preparation"

29. Markku Kulmala (University of Helsinki) "For the one planet we have"

28. Daniel Phifer (Thermo Fisher Scientific) "Overview of Helios 5 DualBeam Technology Advances"

27. Sven Oras (UT/TalTech) and Tauno Tiirats (UT) "Summary of FCC Week"

26. Book presentation: Albert Einstein „Eri- ja üldrelatiivsusteooriast (üldarusaadavalt) and Arthur Stanley Eddington „Füüsikalise maailma olemus“

25. Vijayakumar Anand (UT) "FINCHing objects with a super-resolution – Fundamentals to Applications"

24. Manuel Hohmann (UT), Vitalii Checha (UT), Iaroslav Iakubivskyi (UT), Indrek Jõgi (UT), Maksym Golub (UT), Volodymyr Gulik (UT), Oleksandr Trofymenko (Institute of Safety Problems of Nuclear Power Plants, Ukraine), Leonid Dolgov (UT) "Ukrainian scientists and their contribution to physics and engineering"

23. Indrek Jõgi, Aleksandr Luštšik, Volodymyr Gulik (UT) "Fusion energy record in JET and our contribution to fusion research under EUROfusion"

22. Artur Tamm (UT) "Non-equilibrium processes in molecular dynamics"

2021

21. Kalev Tarkpea (UT) "Integration of the Physics and materials science students into the R&D work of Institute of Physics"

20. Piia Post, Velle Toll, Jaak Kikas (UT) "Nobeli Prize in Physics 2021"

19. Piret Kuusk, Laur Järv (UT) "Book presentation A. Einstein "Üldrelatiivsusteooria põhialus", H. Weyl "Sümmeetria""

18. Adam C. Backer (Apple Inc.) "Pushing the limits of Single Molecule Microscopy"[video]

17. Marco Kirm, Vahur Zadin, Stefan Groote, Heikki Junninen (UT), Triin Kangro (EAS) "Eesti ja CERN" [video]

2020

16. Piret Kuusk, Manuel Hohmann, Rain Kipper, Laur Järv (UT) "Nobeli füüsikapreemia 2020" [video]

15. Kristjan Kunnus (Tartu/Stanford) "Femtosecond Time-Resolved X-ray Spectroscopy and Scattering with X-ray Free Electron Lasers"

14. Laur Järv, Manuel Hohmann, Margus Saal (Tartu) "Laiendatud geomeetrilised gravitatsiooniteooriad"

13. Mikhail Brik (Tartu) "Red for LED"

12. Hasan Yilmaz (Yale) "Coherent control of light transport and imaging through scattering opaque media" [video]

11. Amit Kumar Mishra (Cape Town) "Bio-inspired Methods for Sensing" [video]

10. Manoj K Sharma (Rice University) "Computational imaging"

9. Janek Uin (Brookhaven National Laboratory) "MOSAiC, the largest Arctic expedition" [video]

2019

8. Piret Kuusk, Kaupo Palo, Veiko Palge, Jaan Kangilaski (Tartu) "Madis Kõivu aeg" [video]

7. Jukka Nevalainen, Jaan Einasto, Jaan Pelt, Mihkel Pajusalu (Tartu) "Nobel Prize in Physics 2019"

6. Tõnu Pullerits (Lund) "Ultrafast Spectroscopy of Semiconductor Nanostructures" [video]

5. Laur Järv, Indrek Vurm, Antti Tamm, Christian Pfeifer, Manuel Hohmann (Tartu) "The Dawn of Black Hole Astronomy"

4. Arved Vain (Tartu) "Omnitoni saamise lugu" [video]

3. Alexey E. Romanov (St. Petersburg) "Disclination ensembles in graphene and pseudo-graphenes"

2. Georg Pucker (Bruno Kessler Foundation) "Quantum Silicon Dots"

1. Daniele Faccio (Glasgow) "Imaging with quantum technologies" [video]